Lubricating oil containing a polyamide pour point depressant

ABSTRACT

A lubricating oil composition having improved pour point and dispersancy characteristics comprises a major amount of a lubricating oil and a small amount of a polyamide of a mixture of secondary and tertiary monocarboxylic acids having 19 to 31 carbon atoms in the molecule and a polyalkylene polyamine containing about 2 to about 6 alkylene units, there being from 2 to 4 carbon atoms in each alkylene group, said polyamide containing about 1 to about 3 amine groups in addition to amide groups.

United States Patent Hartle 1 LUBRICATING OIL CONTAINING A POLYAMIDEPOUR POINT DEPRESSANT [75] Inventor: Robert J. Hartle, Gibsonia, Pa.

[73] Assignee: Gulf Research 8: Development Company, Pittsburgh, Pa.

[22] Filed: June 5, 1973 [21] App1.No.: 367,179

[ July 22, 1975 3,405,064 10/1968 Mi11er 44/58 X 1448.048 6/1969 Le Sucrct a1. 252/515 A 3.483.125 12/1969 Clough 7. 252/515 A PrimaryExaminerDelbert E. Gantz Assistant Examiner-Andrew H. Metz [571 ABSTRACTA lubricating oil composition having improved pour point and dispcrsancycharacteristics comprises a major amount of a lubricating oil and asmall amount of a polyamide of a mixture of secondary and tertiarymonocarboxylic acids having 19 to 31 carbon atoms in the mo1ecu1e and apolyalkylene polyamine containing about 2 to about 6 alkylene units,there being from 2 to 4 carbon atoms in each alkylene group. saidpolyamide containing about 1 to about 3 amine groups in addition toamide groups.

11 Claims, N0 Drawings LUBRICATING OIL CONTAINING A POLYAMIDE POUR POINTDEPRESSANT This invention relates to a novel lubricating oil compositionand more particularly to a lubricating composition having improved pourpoint, dispersancy and detergency characteristics.

Lubricants for many present-day internal combustion engines are requirednot only to lubricate and to cool engine parts, but also to maintain theengine parts contacted by the lubricant in clean condition. Uncompoundedlubricating oils are frequently found to be less than fully satisfactorywith respect to the last mentioned function, especially under severeoperating conditions, in that they permit the buildup of carbonaceousdeposits that result not only from deterioration of the oil itself butalso from engine fuel blow-by" contamination. These deposits interferewith proper engine functioning.

In order to improve the ability of oils to maintain an engine in cleancondition. a wide variety of metalorganic compounds (principallyalkaline earth metal salts), such as the calcium, barium, strontium andzinc salts of substituted phenols and petroleum sulfonic acids,salicylates and thiophosphoric acids have been proposed as detergentsand dispersants. Although these metallic salt detergents and/ordispersants have been very useful in maintaining sludge and varnishsuspended in the oil, they have the disadvantage of being themselvessubject to breakdown and deterioration resulting in the formation ofmetallic ash which accumulates in the crankcase and, in some instances,in the combustion chamber of the engine.

In two-cycle engines, lubrication of the engine is accomplished byadmixing the lubricating oil with the gasoline to form an oil-gasolinemixture which functions not only as a lubricant but also as a fuel forthe engine. Inasmuch as the lubricating oil is admixed with the gasolineto form an oil-gasoline mixture which is consumed in the engine, thelubricating oil must be one which when burned in the engine does notadversely affect the operation of the engine. Thus, for example, theoil-gasoline mixture should give prolonged performance without givingrise to spark plug fouling, ring sticking, excessive combustion chamberdeposits, piston or cylinder wall scuffing, scuffing or spalling ofbearings, rusting or corrosion of engine parts, preignition and thelike. Metallic detergents and/or dispersants in lubricating oilcompositions for two-cycle engines are thus undesirable since suchdetergents and/or dispersants upon combustion form a metallic ash whichacts as an abrasive and thus increases the wear of engine parts.

Many metallic detergents and/or dispersants have a further disadvantagein that they lack sufficient basicity to effectively counteract thedeleterious acidic materials which are formed in lubricating oils uponprolonged use under oxidizing conditions. Still further, the metallicdetergents and/or dispersants do not as a general rule enhance the pourpoint characteristics of the lubricating oil to which they are added.The pour point" of an oil is defined as the lowest temperature at whichan oil will pour or flow when chilled without disturbance underspecified conditions.

Various pour point depressors have been described in the literature. Itis already known that certain unsaturated esters, for example, acrylateand methacrylate esters of higher aliphatic alcohols, can be polymerizedto make high molecular weight products which are soluble in lubricatingoils and are capable of reducing the pour point of such oils. It is alsoknown that certain polyamides of mixtures of straightand branched-chainfatty acids and polyalkylene polyamides are capable of reducing the pourpoint of lubricating oils.

By way of illustration of prior art practices, U.S. Pats. Nos. 3,ll0,673 and 3,l69,980 to George J. Benoit, Jr. describe the preparationof polyamides of certain fatty acid mixtures and polyalkylene polyamineswhich are shown to be useful as pour point depressants and detergents inlubricants and fuels. The polyamides which are shown to be useful aspour point depressants are prepared from a critical mixture ofstraight-chain and branched-chain acids and polyalkylene polyamines. Inthese patents, it is taught that to impart improved pour pointcharacteristics to a lubricant, the polyamide must be prepared from apolyalkylene polyamine and a fatty acid mixture, said fatty acid mixturecontaining from about 5 to about 30 mole percent of straight-chain fattyacids and from about to about mole percent of branched-chain fattyacids, said fatty acids containing from about 12 to about 30 carbonatoms each and said polyalkylene polyamine containing from 2 to 6alkylene amine units each, there being from 2 to 4 carbon atoms in eachalkylene group, said polyamide containing from I to 3 amine groups inaddition to amide groups. Specific polyamides shown to be useful includethe polyamide of mixtures of straightand methyl branched-chain C fattyacids and tetraethylenepentamine, said mixtures of fatty acidscontaining from about 5 to about 30 mole percent of stearic acid andfrom about 70 to about 95 mole percent of methyl branched-chainsaturated fatty acid of 18 carbon atoms. These patents show that thepolyamide of a straight-chain fatty acid, i.e., stearic acid andtetraethylenepentamine does not improve the pour point of the base oilbut instead results in a composition having a pour point which is higherthan the pour point of the base oil. These patents show further that thepolyamide of a branched-chain C saturated fatty acid, i.e., a saturated18 carbon atom fatty acid having methyl chain branching andtetraethylenepentamine, neither increases nor decreases the pour pointof the base oil. Thus. these patents teach that a critical mixture ofstraightand methyl branched-chain C fatty acids must be used inproducing the polyamide if the resulting polyamide is to be useful as alubricating oil pour point depressant.

In accordance with the present invention, I have found that the pourpoint and dispersancy characteristics of a lubricating oil can beimproved by incorporating in the oil a small amount of a polyamide of amixture of secondary and tertiary monocarboxylic acids having from 19 to3l carbon atoms, preferably from 19 to 25 carbon atoms in the moleculeand a polyalkylene polyamine containing about 2 to about 6 alkyleneunits, there being from 2 to 4 carbon atoms in each alkylene group, saidpolyamide containing about I to about 3 amine groups in addition toamide groups.

The improved lubricating oil composition of my invention, therefore,comprises a major amount of a lubricating oil and a small amount,sufficient to improve the pour point and dispersancy characteristics ofthe lubricating oil, of a polyamide of a mixture of secondary andtertiary monocarboxylic acids having 19 to 31 carbon atoms, preferably19 to 25 carbon atoms in the 3 molecule and a polyalkylene polyaminecontaining about 2 to about 6 alkylene units, there being from 2 to 4carbon atoms in each alkylene group, said polyamide containing about Ito about 3 amine groups in addition to amide groups.

The present invention is based on the surprising discovery thatlubricating oils containing polyamides derived from a polyalkylenepolyamine and a mixture of secondary and tertiary monocarboxylic acidshaving [9 to 3 l carbon atoms in the molecule having unexpected superiorproperties over lubricating oils containing polyamides derived from apolyalkylene polyamine and a branched-chain saturated fatty acid havingl8 carbon atoms in the molecule. For example, lubricating oilscontaining the polyamides derived from tetrae thylenepentamine and amixture of secondary and tertiary monocarboxylic acids having 19 to 31carbon atoms in the molecule not only have improved pour point.detergency and/or dispersancy properties but also have improved thermaland oxidative stability over lubricating oils containing the polyamidederived from tetraethylenepentamine and a branched-chain monocarboxylicacid having 18 carbon atoms in the molecule, e.g., isostearic acid.

The base oil employed in the lubricating oil composition of theinvention is an oil of lubricating viscosity and can be a mineral oil ora synthetic oil. Synthetic oils which can be used are synthetic oils oflubricating viscosity including, for example, polyalkylene ethers, sili'cones, esters of phosphoric and silicic acids, highly fluorinatedhydrocarbons, polyaryl ethers, aliphatic esters and the like. Mineraloils which can be used are advantageously highly refined paraffinicoils. By the term highly refined" I mean a petroleum lubricating oilwhich has been refined by one of the more drastic refining methods knownin the art, for example, by conventional aluminum chloride refining orby solvent extraction adapted to remove all or substantially all of theunstable constituents of the oil. An aluminum chloride refined and/or asolvent extracted paraffinic base oil, such as Pennsylvania oil.provides an excellent base oil for a composition of the invention.However, drastically refined Mid-Continent and Gulf Coastal oils can beused. A mineral oil which has been treated with hy drogen, whether ahydrofinished or hydrotreated oil, can also be used alone or inadmixture with other oils. The particular base oil which is used willdepend to some extent upon the ultimate use of the lubricating oilcomposition.

In preparing a two-cycle engine lubricating composition having maximumlubricating characteristics, I preferably employ a blend of mineral oilsas the lubricating base. A particularly effective lubricating oil basefor use in two-cycle engine lubricants is a blend of oils consistingessentially of a major proportion of a paraffinic mineral oil distillatehaving a viscosity of about 400 to about 600 SUS at 100 F. (378C) and aminor proportion of a bright stock having a viscosity of about 2500 toabout 4500 SUS at 100 F. (378 C.). The amounts of the paraffinic mineraloil distillate and the bright stock are adjusted so that the viscosityof the lubricating oil blend is about 650 to about 800 SUS at I F. (37.8C.). In general, the blend comprises about 65 to about 85 percent byvolume of the less viscous mineral oil distillate and about to about 35percent by volume of the more viscous bright stock. Bright stock isobtained by dewaxing and clay treating the residue remaining aftervacuum distilling a mineral oil. The amount of the lubricating oil baseemployed in accordance with the invention depends to some extent uponthe ultimate use of the lubricating composition. In general, however,the lubricating oil base comprises about to about 99.9 percent by weightof the lubricating composition.

The mixture of secondary and tertiary monocarboxylic acids suitable foruse in preparing the polyamides can be produced by the acid catalyzedcarboxylation of an alpha olefin having l8 to 30 carbon atoms,preferably 18 to 24 carbon atoms in the molecule. These acids and amethod by which they can be obtained are shown in application Ser. No.367,l77, now US. Pat. No. 3,842,106, by Anatoli Onopchenko and Johann G.D. Schulz entitled COMPOSITION CONTAINING HIGHER FATTY ACIDS filedconcurrently herewith. As described in said application Ser. No.367,l77, now US. Pat. No. 3,842,106, the C to C alpha olefin, preferablya C to C alpha olefin is introduced into a reactor containing sulfuricacid under a carbon monoxide pressure. Water is added to the reactionmixture from which the desired mixture of carboxylic acids having onemore carbon atom than the reactant olefin is recovered. The sulfuricacid which is utilized is substantially anhydrous, that is, from about92 to about I00 percent, preferably 95 to about 98 percent. The molarratio of sulfuric acid to olefin is from about 3:1 to about 20: lpreferably from about Szl to about 10: l. The pressure can be in therange of about I00 to about 5000 pounds per square inch gauge (about 7to about 352 kilograms per square centimeter), preferably in the rangeof about 500 to about 2000 pounds per square inch gauge (about 35.2 toabout 140.8 kilograms per square centimeter), the temperature in therange of about -l5 C. to about 100 C.. preferably about 0 C. to about 40C., and the reaction time about 0.01 to about 12 hours, preferably inthe range of about 0.l to about 4 hours. The reaction mixture, afterdepressuring, is added to water and the mixture of carboxylic acidsformed as a result thereof floats on the surface thereof. The mixture ofacids can then be recovered by decantation. About half of the carboxylicacids obtained are secondary and about half are tertiary. The secondaryand tertiary monocarboxylic acids thus obtained can be defined asfalling within the following two general structures:

Secondary (Iso) Carboxylic Acids (CH l 2 wherein x is the number ofcarbon atoms in the reactant olefin, that is, from 18 to 30 carbonatoms, preferably from about 18 to 24, and n is the integer 2, 3, 4 upto x/2 for even integers between l8 and 30 and 2, 3, 4 up to (.x+l )/2for odd integers between 18 and 30, and

Tertiary (Neo) Carboxylic Acids wherein .r is as defined above. and n isthe integer 2. 3. 4 up to .r/2 for even integers between 18 and 30 and2. 3, 4 up to (x+l )/2 for odd integers between 18 and 30.

The preparation of the mixed secondary and tertiary monocarboxylic acidsuseful in the preparation of the polyamides is illustrated by thefollowing specific examples.

EXAMPLE 1 (Secondary and Tertiary C Monocarboxylic Acids) Into al-liter. 316 stainless steel. magnetically-stirred autoclave containing444 grams of 97 percent aqueous sulfuric acid and under a carbonmonoxide pressure of 1350 pounds per square inch gauge (95.1 kilogramsper square centimeter), there was introduced, with stirring, 224 gramsof l-octadecene. The reaction was allowed to proceed for a period of 4.3hours at a temperature of about 24 C. At the end of the reaction periodthe crude mixture in the autoclave was depressured into a vesselcontaining about I200 grams of wet ice and the organic layer that formedon standing was separated in a separatory funnel and washed severaltimes with approximately an equal volume of a hot percent aqueoussolution of sodium chloride until the final washings were neutral tolitmus paper. On work-up by distillation there was obtained 199.2 grams(78 percent efficiency) of a fraction possessing the following physicalproperties:

Neutral equivalent 3l2 (Theoretical 299) Specific gravity. l5.5 C.0.8820 Viscosity. Centistokes. 98.9 C. 7.09 1 35 C. 3.44 l48 C. 2.77Titer test. C. 1.2 Boiling point. C. 200-205 at about 1.5 mm HgRefractive index. 27.5 C. IASlZ covered fraction: 2-nonadecanoic acid.3- nonadecanoic acid. 4-nonadecanoic acid. 5- nonadecanoic acid.6-nonadecanoic acid, 7- nonadecanoic acid. S-nonadecanoic acid. 9-

nonadecanoic acid. 2-methyl-2-octadecanoic acid. 3-methyl-3-octadecanoic acid. 4-methyl-4-octadecanoic acid.S-methyl-S-octadecanoic acid. 6methyl-6- octadecanoic acid.7-methyl-7-octadecanoic acid. 8-

lit

methyl-S-octadecanoic acid and 9-methyl-9- octadecanoic acid.

EXAMPLE I] (Secondary and Tertiary C Monocarboxylic Acids) About 252grams of l-eicosene and 576 grams of 97 percent aqueous sulfuric acidwere reacted as in Example l for a period of 6 hours at a temperature of30 C. and an initial carbon monoxide pressure of about 1000 pounds persquare inch gauge (70.5 kilograms per square centimeter). On work-up bydistillation there was obtained 248 grams (89 percent efficiency) of aliquid fraction possessing the following physical propertiesz Neutralequivalent 333 (theoretical 32b] Specific gravity, l5.5C. 0.8803 Boilingpoint. C. around 210 at [.2 mm Hg Refractive index. 275C. |.4528

heneicosanoic acid. 4-heneicosanoic acid. 5- heneicosanoic acid.6-heneicosanoic acid. 7- heneicosanoic acid, S-heneicosanoic acid. 9-

heneicosanoic acid and l0-heneicosanoic acid.

EXAMPLE lll (Secondary and Tertiary Mixed C .,-C Monocarboxylic Acids)About 220 grams ofa normal C alpha olefin mixture and 445 grams of 97percent aqueous sulfuric acid were reacted as in Example I for a periodof 4 /2 hours at a temperature of 30 C. and an initial carbon monoxidepressure of about 1350 pounds per square inch gauge (95.1 kilograms persquare centimeter). The alpha olefin feed had an average molecularweight of 295 and contained 3.3 weight percent of l-octadecene. 51weight percent of l-eicosene. 37.9 weight percent of l-docosene and 7.8weight percent of l-tetracosene. On work-up of product by distillationthere was obtained 149 grams (71 weight percent efficiency) of a liquidfraction of C to C carboxylic acids possessing the following physicalproperties:

Neutral equivalent 356 Specific gravity, l5.5C. 0.8789 Viscosity.centistokes,

148C. 3.39 Titer test 0C. l2.9 Boiling point. "C. 220-230 at aboutRefractive index. 275C 1.4536 Iodine Number L4 The mixture obtainedcontains 76 isomers. l6 C carboxylic acids from the C olefin charge. 18C carboxylic acids from the C olefin charge C carboxylic acids from theC olefin charge and 22 C carboxylic acids from the C olefin charge. withhalf of the isomers at an individual carbon number level being secondaryand half being tertiary carboxylic acids.

The alpha olefins which are used in preparing the mixture of secondaryand tertiary monocarboxylic acids for the purposes of this invention areavailable commercially so that neither the alpha olefins per se nor themethod by which they are obtained constitutes any portion of the presentinvention. According to one method which is described in US. Pat. No.2,699.45? which issued on Jan. 11, 1955, to Karl Ziegler and Hans-GeorgGellert. an alpha olefin is obtained by p0 lymerizing ethylene or amixture of ethylene with other unsaturated hydrocarbons at a temperatureof about 60 to about 250 C. in the presence of a metal polymerizationactivator comprising a metal selected from the group consisting ofberyllium, aluminum, gallium and indium having the valence linkagesthereof individually bound to members selected from the group consistingof hydrogen, monovalent saturated organic hydrocarbon radicals andmonovalent aromatic organic hydrocarbon radicals.

The alpha olefins used in preparing the secondary and tertiary C C andmixed Cry-C25 monocarboxylic acids of Examples 1, I1 and Ill have thefollowing typical characteristics.

e.g., Polyamine H, which comprises a mixture of cyclic, straightandbranched-chain components are also acceptable reactants.

The polyalkylene polyamines are available commercially so that neitherthe polyalkylene polyamines per se nor their method of preparationconstitutes any portion of the present invention. The polyalkylenepolyamines, for example, can be prepared by reacting ammonia with analkyl dihalide.

The polyamides suitable for use in preparing a lubrieating compositionof the present invention can be prepared according to known methods.These polyamides and a method by which they can be obtained are shown inapplication Ser. No. 367,180 and now U.S. Pat. No. 3,864,368, by Robert.I. Hartle entitled A POLYAM- lDE OF A MIXTURE OF SECONDARY AND TER-TlARY MONOCARBOXYLIC ACIDS filed concurrently herewith. As described insaid application Ser. No. 367.180 and now US. Pat. No. 3,864,368, thepolyamides can be prepared by reacting the mixture of secondary andtertiary carboxylic acids and the polyalkylene polyamine at atemperature of about 250 to about 500 F. 121 to about 260 C.) untilreaction is substantially complete. The reaction may require a pe riodof about 1 to about 24 hours. Inasmuch as water is formed in thereaction, completion of the reaction is aided by removal of the watersubstantially as fast as it is formed. Removal of the water isadvantageously ef- Eicosenem) Ocladecene- 1 Octadecene-l toTetracosene-l Mixture iil' u) Specific Gravity,

ASTM D1 298:

Open cup method The polyalkylene polyamines useful in preparing thepolyamides for the purposes of this invention include those having theformula fected by heating the reaction mass at a reduced pressure, i.e.,pressure less than atmospheric.

Formation of the polyamides is believed to involve at least a two-stepreaction between the carboxylic acid mixture and the polyalkylenepolyamine. The proportions of the carboxylic acid mixture and thepolyalkylene polyamine may be such that the moles of carboxylic acid areequal to the molar equivalents of amine groups in the polyalkylenepolyamine. However, it is preferred to employ from about 1 to about 3moles less acid than the number of available amino groups in thepolyamine. The product of the reaction is theoretically a polyamidewhich contains an average of three amido groups and two free aminogroups per molecule. The acyl groups may be attached to any of thenitrogen atoms in a manner such that there is an overall statisticalaverage of 3 acyl groups per polyamide molecule. The reaction betweenthe carboxylic acid and the polyalkylene polyamine is believed toproceed in accor- 9 dance with the following representative equations,it being understood that the acyl groups may be attached to any of thenitrogen atoms to give an overall average of 3 acyl groups per polyamidemolecule.

tetraethylenepentamine (26.33 amine equivalents). The amine is heated to125 C. with stirring in a nitrogen atmosphere. The addition of a mixtureof secondary and tertiary C monocarboxylic acids obtained by 5 thesulfuric acid catal zed carbox lation of a C alpha 3 RCOOH NH'(CH2CH2NHhH Amine Salt olefin as set forth in Example I is thenstarted. A total of 5079 grams 16.28 equivalents of acid) is added inmine salt 4 a a slow stream over a period of 2.5 hours whilekeeping thetemperature at l25l40 C. After addition of the RCONH (CH CH NHl CH CHNCH CH NHCOR 3H O l0 acid is complete, the reaction mixture is stirredat 150 C. for 1 hour. The temperature is then increased to 195 C. andheld at this temperature for about 3 hours with rapid stirring whilenitrogen is bubbled slowly The amount of the polyamide added to thelubricatthrough the mixture. At the end of the 3 hour period ing oilbase in accordance with the present invention is about 50 percent of thetotal theoretical amount of that amount which is sufficient to improvethe pour water is evolved. The nitrogen tube is then replaced by pointand dispersancy characteristics of the lubricant. a fine capillary andwater aspirator vacuum is applied The minimum and optimum effectiveproportions can to the system. Heating at 195 C. is continued at -30vary somewhat depending upon the nature of the parmm Hg for 2.5 hours.Total water evolved at this time ticular polyamide and the ultimate useof the lubricat- 20 i b t 72% of theoretical. An oil-pump vacuum (5 ingcomposition. In general, the polyamide is incorpomm Hg) i then appliedand heating is continued at rated in a lubricating oil base in an amountof about 0.1 [95 C. for about 7 hours. Total water Collected at the toabout 15 percent by weight of the lubricating oil end of this seven hourperiod is 87 percent of theoreticomposition. Good pour point anddispersancy characcal. No evidence of further reaction is observed. Theteristics have been obtained in lubricants containing Product 902 grams)sa leanthiekamber fluid havabout 1 to about 10 percent by weight of thepolyaming the following analysis: ides of the C to C31 monocarboxylicacids and tetraethylenepentamine. I The polyamides described herein canbe incorpo- 3 22 g ci z rated in a wide variety of lubricating oilbases, such as Niiro nfik B weigiu for example, lubricants for two-cycleoutboard engines, 159 marine diesel engines, gasoline and dieselautomotive Acid Number A51-M D664 engines, stationary internalcombustion engines and the T0131 Base Number 105 like. Free Base, bytitration to pH 3 2.03 meq/g Specific Gravlty. (AF/60F. The preparationof polyamides useful in the composi- (15.5/l5.5C.] 0.9226 tions of thisinvention is illustrated by the following specific examples. When theprocedure of Example IV is repeated using a mixture of secondary andtertiary C monocarbox- EXAMPLE [V ylic acids from Example II and amixture of secondary A 12 liter flask, equipped with stirrer,thermometer, and tertiary mixed C monocarboxylic acids from probe fortemperature controller and recorder, nitro- Example lll, instead of amixture of secondary and tergen inlet and take-off condenser, is flushedwith dry nitiary C monocarboxylic acids, the polyamide product trogenand charged with 1107 grams of commercial analyses shown in Table l areobtained.

TABLE 1 Product Analysis Free Base Total Acid Molar Ratio ReactionConditions Nitrogen, wt% meq/g No. Example No. Acid ReactantAcid/'I'IEPA Temp. 6C. Hours Total Basic (to pH3) ASTM D664 V Secondaryand 3.28 205 7 5.46 3.15 1.74

Tertiary C2, monocarboxylic acids (Example II) VI Secondary and 3.23 94.80 2.72 1.48 55 Tertiary C -C monocarboxylic acids (Example I") VIISecond and 2.00 195 [3 7.11 5.00 37 Tertiary .Cg

monocarboxylic acids (Example Ill] '"I'EPA tetraethylenepentamine "Firsttwo hours at atmospheric pressure. Remainder at 30 mm Hg or lower.

The herein described polyamides can be incorporated in the lubricatingoil in any convenient way. Thus, the polyamide can be added directly tothe lubricating oil by thoroughly blending the polyamide in thelubricating oil at the desired level of concentration. Alternatively.the polyamide can be blended with suitable solvents to form concentratesthat can be readily dissolved in the appropriate lubricating oils at thedesired concentrations. The concentrate should contain at least lpercent by weight of the polyamide pour point depressant and preferablyabout 25 to about 65 percent by weight of the polyamide. The solvent insuch a concentrate may be present in amounts of about 35 to about 90percent by weight. The solvent preferably boils within the range ofabout 38 to about 37l C. depending upon the ultimate use of thelubricating oil composition. Suitable solvents which can be used forthis purpose are naphtha, kerosene, benzene, xylene, toluene, hexane,light mineral oil. stoddard solvent and mixtures thereof. The particularsolvent selected should, of course. be selected so as not to adverselyaffect the other desired properties of the ultimate lubricating oilcomposition, Thus, if the lubricating oil is to be used as a two-cycleengine lubricant, the solvent should preferably burn without leaving aresidue and should be non corrosive with respect to metal. specificallyferrous metals.

in order to illustrate the improved pour point charac teristics of alubricating oil when compounded in accordance with the presentinvention, pour points (ASTM D97) were obtained on a lubricating oilbase with and without the addition of the polyamides of the mixedsecondary and tertiary C to C monocarboxylic acids produced in the acidcatalyzed carboxylation of the C to C alpha olefins andtetraethylenepentamine as described in Examples IV, V and Vi. The baseoil used in illustrating the invention is a blend of 86 percent byvolume of a hydrofinished lubricating oil (600 SUS at 100 F. [378 C.]and 68.7 SUS at 2l0 F. [989 C.]) and I4 percent by volume of a brightstock (2572 SUS at 100 F. [37.8 C.] and 155 SUS at 2l0 F. [98.9" C.]).The base oil has the following typical characteristics:

Grin ity. API 28.2 Viscosity, SUS

at lOU F, (37.3 CJ 700 at 2 HP F. (939 C.) 74.6 Flash point, P-M, Cr H83Fire point, CC. C. 296.| Pour point. +5 F. (-l5C.J

The test results are shown in the following Table II.

TABLE 11 Lubricating Composition As shown by the test results summarizedin Table II. the polyamides of the mixed secondary and tertiary C(Example lV), C21 (Example V) and mixed C to C (Example VI)monocarboxylic acids produced by the acid catalyzed carboxylation of theC to C alpha olefins (Examples I, II and Ill) and tetraethylenepentamineimpart improved pour point characteristics to a lubricating oil base,although optimum improvement is obtained at different concentrationlevels with the vari ous polyamides. While a maximum pour pointimprovement with the polyamide prepared from the secondary and tertiaryC monocarboxylic acids requires 9 percent by weight of polyamide,maximum pour point improvement with the polyamide prepared from themixed secondary and tertiary C and the mixed secondary and tertiary C toC monocarboxylic acids can be obtained with as little as 1 percent byweight of the polyamide. Thus, in accordance with the present invention,for economic reasons, the polyamides prepared from the mixed secondaryand tertiary C acids and the mixed secondary and tertiary C to Cmonocarboxylic acids are preferred.

As indicated hereinabove. the lubricating oil composition of theinvention can be utilized as a two-cycle engine lubricating oilcomposition. To illustrate this use. a lubricating oil composition wasprepared by blending 60.6 percent by volume ofa hydrofinished neutralmin' eral oil (600 SUS at F. [378 C.[ and 68.7 SUS at 2l0 F. [98.9"C.]), l0.0 percent by volume of a bright stock (2572 SUS at [00 F. [378C.[ and l55 SUS at2l0 F. [989 C.]), 20.0 percent by volume of stoddardsolvent and 9.4 percent by volume of the polyamide reaction product ofExample lV. One volume of the lubricating oil composition thus obtainedwas blended with 50 volumes of leaded regular grade gasolines. The fuelsthus obtained were employed in l00 horsepower and 50-horsepower outboardengines. The test procedure employed in the outboard engines wasconducted, except for a change in ratio of gasoline to lubricant, inaccordance with the Outboard Boating Club (O.B.C.) Outboard TestProcedure. The test procedure which was used was altered from thatestablished by the O.B.C. in that l employed a gasoline to lubricantvolume ratio of 50:l instead of 20:] as recommended by the O.B.C.According to the O.B.C. procedure. the engine is operated for 100 hoursof cyclic opcration, each cycle consisting of 55 minutes at fullthrottle and 5 minutes at an idling speed. During the 5- minute idle.there are 5 rapid accelerations to wide TABLE III LubricatingComposition, 7r by Volume Neutral mineral oil (600 SUS at 100 F. [37.8"C. 1; 68.7 SUS at 2l0 F, I985? C. 606 Bright stock (2572 SUS at 100 F.

[37.8" C.[; SUS at 2l0 F.

[989 (.l] l().() Stoddard solvent 20.0 Polyamide product of Example IV94 Inspection (iravil 'API 3 l .3

TABLE Ill-Continued ll) 71.9 light to medium Piston or Cylinder WallScuffing nil Number of instances of Preignition nil nil Condition ofBearings. pitting nil nil Spark Plug Failures I nil As shown by the datain Table III, the lubricating composition of the invention givesexcellent engine cleanliness ratings and freedom from preignition evenwhen used with a leaded gasoline in a two-cycle engine. The ring wearand combustion chamber deposits are also satisfactory. In addition,there is no evidence of piston or cylinder wall scuffing and no evidenceof connecting rod or piston pin needle bearing pitting.

As disclosed hereinabove, lubricating oils containing polyamides derivedfrom tetraethylenepentamine and a mixture of secondary and tertiarymonocarboxylic acids having 19 to carbon atoms in the molecule not onlyhave improved pour point. detergency and/or dispersancy properties butalso have improved thermal and oxidation stability over lubricating oilscontaining the polyamide derived from tetraethylenepentamine and abranched-chain monocarboxylic acid having 18 carbon atoms in themolecule. e.g.. isostearic acid. In order to illustrate thethermal-oxidation and deposition characteristics of compositions of theinvention containing polyamides derived from a polyalkylene polyamineand mixed secondary and tertiary monocarboxylic acids having l9 to 25carbon atoms in the molecule in comparison with a polyamide derived fromthe same polyalkylene polyamine and a branched-chain monocarboxylic acidhaving l8 carbon atoms in the molecule, e.g.. isostearic acid.lubricating compositions containing the products of Examples IV and VIIwere compared in the Alcor Deposition Test with a lubricatingcomposition containing the isostcaric acid triamide oftetraethylenepentamine. The Alcor Deposition Test unit is designed forservice evaluation of fluid lubricant thermal-oxidation degradation anddeposition characteristics. The Alcor Deposition Test comprisescontinuously circulating aerated test fluid through a filter and throughthe annular space between an electrically heated tube and a concentrichousing. The entire test unit is enclosed in an electrically heatedcabinet. In conducting the test. 250 ml of test oil is circulated continuously by a constant speed pump from a cooler/- sump through theannular space between an electricaIly heated tube and concentric housingand back to the cooler/sump. Air saturated with water is injected intothe circulating oil just before it enters the heater tube annulus. Onleaving the heater tube annulus. the air/oil mixture returns to thecooler/sump; excess air is vented and oil temperature is kept constantby air cooling. Cooler/sump oil level is maintained by automatic feedfrom a makeup reservoir. The cooler/sump base houses a mesh oil filter.The test conditions can be varied so long as they are constant for agiven series of tests. The oil temperature can be varied to about 370 C.but is usually maintained at about C. The heater tube temperature can bevaried to about 535 C., but is usually maintained within the range ofabout 150 to about 3 l5 C. The air injection can be varied to i000 mlper minute. The oil flow rate is fixed at 300 ml per minute. The cabinettemperature can be varied to about 315 Cv but is usually maintainedabout 40 C. below the oil temperature. The duration of the test can bevaried. but is usually 24 or 48 hours. At the conclusion of the test,the deposits in the tube are weighed. A deposit rating is obtained bysumming the products of each per inch of heater tube rating times thecorresponding per inch heater tube deposit weight. then dividing by 10.Filter deposits are determined by noting the increase in filter weightafter the test. This measurement provides a measure of sludge and thetendency of particulate matter to flake off the heater tube duringtesting. The overall rating is determined by summing the tube deposits,the deposit rating and filter deposits and then dividing by 2. Thisprovides a single reference point for assessment of overall depositcharacteristics. An overall rating that is low indicates lubricantstability and resistance to thermal and oxidative degradation anddeposit formation. Relatively small changes in neutralization number andviscosity of the lubricant during the test is another indication ofresistance to degradation. The make-up of the lubricating compositionsevaluated in the Alcor Deposition Test and the results of theevaluations are summarized in Table IV.

TABLE IV Test Conditions: Lower Tube Temp., C. 260 Oil-in Temp, C. 150Cabinet Temp. C. 93.3 Air Flow cc/min 1,000 Test Duration, Hours 24Lubricating Composition. By Volume A B C Neutral mineral oil (600 SUS atl0OF. [37.8"C.]; 68.7 SUS at 210F.

l98.9C.l) 78.3 78.3 78.3 Bright Stock (2572 SUS at 100F. [318C]; I55 SUSat 2l0F. [98.9C.|) 12.7 12.7 l2.7 Polyamide product of Example IV 9.0Polyamide product of Example VII 9.0 Polyamide of isostearic acid andtetraethylenepentamine" 9.0

TABLE IV Continued Test Conditions: Lower Tube Temp., C. 260 Oil-inTemp, C. 150 Cabinet Temp, C. 93.3 Air Flow cc/min 1.000 Test Duration.Hours 24 Lubricating Composition. By Volume A B C BL S L'L CriticalTemp. "C. 285 30l .7 304.4 Deposits Rating 37.3 17.6 26.0 Tu e Deposits.mg. 26.5 20.3 [5.0 Filter Deposits. mg. 47.2 36.3 i967 Oil Consumption.ml. 40 20 30 Overall Rating (0 is clean) 55 37 1004 Viscosity. SUS at100F. (378C). lnitial BlZ 802 854 24 hours 982 954 [058 "/r Increase20.) I89 23.9

Total Acid No, initial 53 3.0 0.57 24 hours 6.0 4.5 2.80 change +0.7+1.5 +2.23

'lsostean'c acid triarnide of tetraethylenepentamine 7c Nitrogen (Total.6.30; Basic, 2.34)

As shown by the data in Table IV. the lubricating I claim:

compositions of the invention (Compositions A and B) have goodresistance to degradation and deposit formation in comparison with acomposition not within the scope of the invention (Composition C). Itwill be noted that Compositions A and B had filter deposits of 47.2 mgand 36.3 mg, respectively whereas Composition C had filter deposits ofl967 mg. Furthermore, the overall rating of Compositions A and B were 55and 37, respectively. whereas the overall rating of Composition C was1004 The percentage increase in viscosity after 24 hours was greater forComposition C than for either Composition A or Composition B. Likewise.the change in total acid number for Composition C was greater than thechange in total acid number for either Composition A or Composition B.In summation, the data show that lubricating compositions which containthe poly-amides of mixed secondary and tertiary monocarboxylic acidshaving 19 to 25 carbon atoms per molecule and tetraethylenepentamine aresurprisingly more resistant to thermal and oxidative degradation anddeposit formation than a lubricating composition which contains thepolyamide of a branched-chain monocarboxylic acid having l8 carbon atomsin the molecule (isostearic acid) and tetraethylenepentamine.

The lubricating composition of this invention can contain conventionallubricant additives, if desired, to improve other specific properties ofthe lubricant without departing from the scope of the invention. Thus.the lubricating composition can contain a corrosion and rust inhibitor.an extreme pressure agent, an antioxidant. an antifoamant, a metaldeactivator, a viscosity index improver, a sludge inhibitor. athickener, a dye and the like. Whether or not such additives areemployed and the amounts thereof depend to a large extent upon theseverity of the conditions to which the composition is subjected andupon the stability of the lubricating oil base in the first instance.When such conventional additives are employed they are generally addedin amounts between about 0.01 and 5 percent by weight based on theWeight of the total composition.

While my invention has been described with reference to various specificexamples and embodiments. it will be understood that the invention isnot limited to such examples and embodiments and may be variouslypracticed within the scope of the claims hereinafter made.

l. A lubricating composition comprising a major amount of a lubricatingoil and a small amount, sufficient to improve the pour point anddetergencydispersancy characteristics of the lubricating oil. of apolyamide of a mixture of about equal amounts of secondary and tertiarymonocarboxylic acids and a polyalkylene polyamine containing about 2 toabout 6 alkylene units, there being from 2 to 4 carbon atoms in eachalkylene group, said mixture of secondary and tertiary monocarboxylicacids falling within each of the following general structures Cilii-C-COOl-l wherein x is a number from 18 to 30 and n is the integer 2,3. 4 up to x/2 for even integers between 18 and 30 and 2, 3, 4 up to(.r-i-l )/2 for odd integers between 18 and 30. said polyamidecontaining about I to about 3 amine groups in addition to amide groupsand being the product obtained by reacting said polyalkylene polyamineand said mixture of secondary and tertiary monocarboxylic acids at atemperature of about 250 F. (121 C.) to about 500 F. (260 C.) until therear. tion is substantially complete. the proportion of said carboxylicacid mixture and the polyalkylene polyamine being such that there arefrom about i to about 3 moles less acid than the number of availableamino groups in the polyamine.

2. A lubricating composition according to claim 1 wherein said polyamidecomprises about Oil to about percent by weight of the lubricating oilcomposition.

3. A lubricating composition according to claim 1 wherein saidpolyalkylene polyamine is tetraethylenepentaminei 4. A lubricatingcomposition according to claim 3 wherein x is a number from 18 to 24.

5. A lubricating composition according to claim 4 wherein said polyamidecomprises about 1 to about it) percent by weight of the lubricating oilcomposition.

6. A lubricating composition according to claim 3 wherein x is 18.

7. A lubricating composition according to claim 6 wherein said polyamidecomprises about 1 to about It) percent by weight of the lubricating oilcomposition.

8. A lubricating composition according to claim 3 wherein x is 20.

9. A lubricating composition according to claim 8 wherein said polyamidecomprises about 1 to about 10 percent by weight of the lubricating oilcomposition.

10. A lubricating composition according to claim 3 wherein .r is amixture of even numbers from 18 to 24.

11. A lubricating composition according to claim 10 wherein saidpolyamide comprises about 1 to about [0 percent by weight of thelubricating oil composition.

1. A LUBRICATING COMPOSTION COMPRISING A MAJOR AMOUNT OF A LUBRICATINGOIL AND A SMALL AMOUNT, SUFFICIENT TO IMPROVE THE POUR POINT ANDDETERGENCY-DISPERSANCY CHARACTERISTICS OF THE LUBRICATING OIL, OF APOLYAMIDE OF A MIXTURE OF ABOUT EQUAL AMOUNTS OF SECOND ARY AND TERTIARYMONOCARBOXYLIC ACIDS AND A POLYALKYLENE POLYAMINE CONTAINING ABOUT 2 TOABOUT 6 ALKYLENE UNITS, THERE BEING FROM 2 TO 4 CARBON ATOMS IN EACHALKYLENE GROUP, SAID MIXTURE OF SECONDARY AND TERTIARY MONOCARBOXYLIXACIDS FALLING WITHIN EACH OF THE FOLLOWING GENERAL STRUCTURES
 2. Alubricating composition according to claim 1 wherein said polyamidecomprises about 0.1 to about 15 percent by weight of the lubricating oilcomposition.
 3. A lubricating composition according to claim 1 whereinsaid polyalkylene polyamine is tetraethylenepentamine.
 4. A lubricatingcomposition according to claim 3 wherein x is a number from 18 to
 24. 5.A lubricating composition according to claim 4 wherein said polyamidecomprises about 1 to about 10 percent by weight of the lubricating oilcomposition.
 6. A lubricating composition according to claim 3 wherein xis
 18. 7. A lubricating composition according to claim 6 wherein saidpolyamide comprises about 1 to about 10 percent by weight of thelubricating oil composition.
 8. A lubricating composition according toclaim 3 wherein x is
 20. 9. A lubricating comPosition according to claim8 wherein said polyamide comprises about 1 to about 10 percent by weightof the lubricating oil composition.
 10. A lubricating compositionaccording to claim 3 wherein x is a mixture of even numbers from 18 to24.
 11. A lubricating composition according to claim 10 wherein saidpolyamide comprises about 1 to about 10 percent by weight of thelubricating oil composition.